1. Field of the Invention
The present invention relates to a method for the control of a filling machine for the filling of containers with liquid filling material, preferably for the control of a rotary filler for the filling of beverage containers with beverages.
2. Description of Related Art
Filling machines and especially rotary fillers for the filling of liquid filling material into containers are well known in the prior art. Known filling machines typically comprise filling elements through which the liquid filling material is passed to reach the respective containers to be filled. Usually the respective filling process is started at a specified machine position, i.e. at the start of the filling angle, and is terminated upon reaching a specified final condition. The final condition for the filling process may for example be a filling quantity, a filling weight or a filling level to be reached in the respective container. By means of an appropriate filling sensor this final condition is monitored. If the final condition will not be reached before the end of the filling angle the filling method is necessarily terminated upon reaching the end of the filling angle.
During the actual filling process the filling element may provide different flow rates which are controlled according to a specified routine. For example, to avoid excessive foaming, a lower flow may be provided at the beginning of the filling process. During an intermediate period maximal flow may then be provided to accomplish rapid filling of the container. Upon reaching the end of the filling process reduced flow rate may in turn be provided to facilitate exact filling of the container and reaching the final condition without any problems.
The filling sensor for the detection of the presence of the final condition is for example given in form of a flow sensor for the determination of the flow rate of the liquid filling material through the filling element, a weight sensor or a weighing cell for the determination of the filling weight of the liquid filling material in the container, a back pressure sensor in a Pitot tube or a short circuit sensor on a probe for the determination of a specified filling level in a container, or a volume sensor for the determination of the filling volume introduced into the container. Upon reaching the specified volume, the specified quantity, the specified weight and/or the specified filling level the filling element will be closed and the filling process for this container is terminated.
If such a filling sensor for the determination of filling termination of a filling element in a filling machine fails, filling termination may no longer be exactly determined. Overfilling of the container will result since the filling element will not terminate before the end of the filling angle, i.e. at a point in time which is specified by the machine position—independent of the proper filling state of the container. The resulting overfilled bottle is identified as a defective filling and must be eliminated from the system. Basically, in a rotary filler in each filling cycle such an overfilled container is generated so that the performance will significantly be compromised. Simultaneously, increased contamination of the filling machine by the overflow of the respective overfilled containers may occur.
In the known filling methods the problem of a defective filling sensor is solved by way of completely shutting down the affected filling element. In this way generation of overfilled containers is avoided. From shutting down the affected filling element, however, a loss of filling performance will result since with each filling element which is shut down filling performance will get lost. Furthermore, upon shutting down the affected filling element in each filling cycle an empty container is produced for each shut down filling element which as well has to be eliminated in the following quality control process.
From DE 10 2006 029 490 B4 it is known to measure the filling time required by an intact filling sensor and to control a filling element having a defective filling sensor on the basis of said identified filling time. In this way by using the filling time which was measured for an intact filling element the filling element with the defective filling sensor may still be operated. For this, the valve opening signal for the defective filling element must be delayed to accomplish opening and closing of the defective filling element in correspondence to the desired machine angle or the desired position within the filling machine, respectively.
The known method suffers from the fact that for obtaining measurement of the filling time of the intact filling element at least one revolution of the filling machine must be passed. Accordingly, upon occurrence of failure of a filling sensor at least two defectively filled containers are generated, i.e. a first defectively filled, overfilled container, allowing to assume failure of the filling sensor in the first place, and a second defectively filled container which either is also overfilled or which, having a shut down filling element, is underfilled accordingly, while the filling time of a filling element having an intact filling sensor is being determined.